Finding the Pitch of your roof

There are several methods for doing this. A trained eye can usually guess the pitch just by looking at it, but you can find it very easily with a small level and a speed square. Just get a ladder and position yourself at a gable end. Climb up to where a good portion of the rake is eye level. Place the level so one end is laying on the roof. A small spirit level is real good for this. Leaving this end on the roof, raise or lower the other end until it is level. Now use your speed square by placing it´s 90 degree corner at the point where the level meets the roof. Speed squares already have a degree mark on them, and if you read where the roof angle is on the opposite of the corner, it will tell you the angle of the roof. Refer to the chart below to figure out the pitch. It only goes from 3 in 12 to a 12 in 12, if yours is higher, you´ll have to use the next method, and hope you never have to roof it. :)

Angle vs. Pitch

• 45 -> 12 in 12
• 39.75 -> 10 in 12
• 33.75 -> 8 in 12
• 30.25 -> 7 in 12
• 26.5 -> 6 in 12
• 22.5 -> 5 in 12
• 18.5 -> 4 in 12
• 14 -> 3 in 12

Another Method

The other method takes a little longer to prepare, but you don´t have to translate angles to pitch. Get a board about 2 feet long and place a mark exactly 12 inches from one end. Lay this board on the roof with the end you measured from pointed towards the pitch. Now lay your level on top of the board and support the other end so that it is level. Use a ruler or tape measure to measure the distance at the mark on the board to the level, straight up. If you get a 4, for example, the roof rises 4´ in 12´ and is a 4/12 roof.

Making the Cut

Whatever method you chose, you will have to transfer that to the corner piece, and the best tool for that is the speed square. This time though, you just match up the corner and the angle and mark where to cut. Most of the time there are other obstacles, such as adjoining soffit, that you must notch around. This is why you start all the way on the end to allow room for modifying the cut.

Test the Fit

Place the corner up against the soffit and see how it fits. Have a helper hold it in place while you climb the ladder to get a better look at it. Make marks where you need to trim and try to give it a good fit. It does not have to be tight though, siding must move as it expands and cools. You don´t want it looking sloppy, but an 1/8 of an inch gap in most cases is acceptable. Now let's cut some corners!